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Reward sensitivity deficits modulated by dopamine are associated with apathy in Parkinson ’ s disease

View Article: PubMed Central - PubMed

ABSTRACT

Apathy is extremely common in neurodegenerative disorders such as Parkinson’s disease. Muhammed et al. report that lack of sensitivity to rewards may underlie apathy, with dopamine playing a modulatory role. The study provides a basis for objective clinical markers of motivation and treatment efficacy in neurodegenerative conditions.

No MeSH data available.


Related in: MedlinePlus

Pupillary responses in apathetic vs non-apathetic Parkinson’s disease cases. (A) Mean pupil reward sensitivity over 1400–2400 ms in apathetic Parkinson’s disease patients (cyan) was significantly reduced compared to non-apathetic patients (green) both ON and OFF dopaminergic medication. There was an increase in reward sensitivity in both apathetic and non-apathetic patients when ON dopamine, but no significant interaction between the drug state and apathy level. Comparison of average pupil reward sensitivity between apathetic and non-apathetic Parkinson’s disease patients to elderly controls (grey) showed a significant reduction in reward sensitivity in apathetic Parkinson’s disease patients when OFF dopamine and greater reward sensitivity in non-apathetic Parkinson’s disease patients when ON. (B) A significant correlation between average pupil reward sensitivity in Parkinson’s disease patients ON and their clinical interview LARS score. More apathetic patients exhibit less pupillary reward sensitivity compared to more motivated patients. (C) A significant correlation between pupil reward sensitivity and clinical interview LARS in Parkinson’s disease OFF.
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aww188-F4: Pupillary responses in apathetic vs non-apathetic Parkinson’s disease cases. (A) Mean pupil reward sensitivity over 1400–2400 ms in apathetic Parkinson’s disease patients (cyan) was significantly reduced compared to non-apathetic patients (green) both ON and OFF dopaminergic medication. There was an increase in reward sensitivity in both apathetic and non-apathetic patients when ON dopamine, but no significant interaction between the drug state and apathy level. Comparison of average pupil reward sensitivity between apathetic and non-apathetic Parkinson’s disease patients to elderly controls (grey) showed a significant reduction in reward sensitivity in apathetic Parkinson’s disease patients when OFF dopamine and greater reward sensitivity in non-apathetic Parkinson’s disease patients when ON. (B) A significant correlation between average pupil reward sensitivity in Parkinson’s disease patients ON and their clinical interview LARS score. More apathetic patients exhibit less pupillary reward sensitivity compared to more motivated patients. (C) A significant correlation between pupil reward sensitivity and clinical interview LARS in Parkinson’s disease OFF.

Mentions: Does reward sensitivity alter with Parkinson’s disease compared to controls or with apathy in Parkinson’s disease on this task? Taking into account all the data (control participants and Parkinson’s disease patients ON and OFF dopamine and drug-naïve) a linear mixed effects model was performed on average pupil reward sensitivity (difference between 0p and 50p reward level over the 1000 ms epoch) for each individual participant. This being the highest level of analysis, overall there was no difference between Parkinson’s disease patients and elderly controls [F(1,96) = 0.02, P = 0.9]. There was, however, a main effect of apathy [F(1,96) = 11.2, P < 0.01] with the apathetic Parkinson’s disease group demonstrating significantly reduced pupillary responses to reward than the non-apathetic group (Fig. 4A). Furthermore, while all comparisons between reward levels in the non-apathetic group were significant (P < 0.003 between each reward magnitude), none were so in the apathetic group, indicating that pupillary response to reward is blunted in apathy.Figure 4


Reward sensitivity deficits modulated by dopamine are associated with apathy in Parkinson ’ s disease
Pupillary responses in apathetic vs non-apathetic Parkinson’s disease cases. (A) Mean pupil reward sensitivity over 1400–2400 ms in apathetic Parkinson’s disease patients (cyan) was significantly reduced compared to non-apathetic patients (green) both ON and OFF dopaminergic medication. There was an increase in reward sensitivity in both apathetic and non-apathetic patients when ON dopamine, but no significant interaction between the drug state and apathy level. Comparison of average pupil reward sensitivity between apathetic and non-apathetic Parkinson’s disease patients to elderly controls (grey) showed a significant reduction in reward sensitivity in apathetic Parkinson’s disease patients when OFF dopamine and greater reward sensitivity in non-apathetic Parkinson’s disease patients when ON. (B) A significant correlation between average pupil reward sensitivity in Parkinson’s disease patients ON and their clinical interview LARS score. More apathetic patients exhibit less pupillary reward sensitivity compared to more motivated patients. (C) A significant correlation between pupil reward sensitivity and clinical interview LARS in Parkinson’s disease OFF.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5035817&req=5

aww188-F4: Pupillary responses in apathetic vs non-apathetic Parkinson’s disease cases. (A) Mean pupil reward sensitivity over 1400–2400 ms in apathetic Parkinson’s disease patients (cyan) was significantly reduced compared to non-apathetic patients (green) both ON and OFF dopaminergic medication. There was an increase in reward sensitivity in both apathetic and non-apathetic patients when ON dopamine, but no significant interaction between the drug state and apathy level. Comparison of average pupil reward sensitivity between apathetic and non-apathetic Parkinson’s disease patients to elderly controls (grey) showed a significant reduction in reward sensitivity in apathetic Parkinson’s disease patients when OFF dopamine and greater reward sensitivity in non-apathetic Parkinson’s disease patients when ON. (B) A significant correlation between average pupil reward sensitivity in Parkinson’s disease patients ON and their clinical interview LARS score. More apathetic patients exhibit less pupillary reward sensitivity compared to more motivated patients. (C) A significant correlation between pupil reward sensitivity and clinical interview LARS in Parkinson’s disease OFF.
Mentions: Does reward sensitivity alter with Parkinson’s disease compared to controls or with apathy in Parkinson’s disease on this task? Taking into account all the data (control participants and Parkinson’s disease patients ON and OFF dopamine and drug-naïve) a linear mixed effects model was performed on average pupil reward sensitivity (difference between 0p and 50p reward level over the 1000 ms epoch) for each individual participant. This being the highest level of analysis, overall there was no difference between Parkinson’s disease patients and elderly controls [F(1,96) = 0.02, P = 0.9]. There was, however, a main effect of apathy [F(1,96) = 11.2, P < 0.01] with the apathetic Parkinson’s disease group demonstrating significantly reduced pupillary responses to reward than the non-apathetic group (Fig. 4A). Furthermore, while all comparisons between reward levels in the non-apathetic group were significant (P < 0.003 between each reward magnitude), none were so in the apathetic group, indicating that pupillary response to reward is blunted in apathy.Figure 4

View Article: PubMed Central - PubMed

ABSTRACT

Apathy is extremely common in neurodegenerative disorders such as Parkinson&rsquo;s disease. Muhammed et al. report that lack of sensitivity to rewards may underlie apathy, with dopamine playing a modulatory role. The study provides a basis for objective clinical markers of motivation and treatment efficacy in neurodegenerative conditions.

No MeSH data available.


Related in: MedlinePlus